Selection and scaling of real accelerograms for bi-directional loading: A review of current practice and code provisions

The seismic behavior of asymmetric building structures is often complex and reductions to plane problems which can be analyzed with a single horizontal ground-motion component are often deemed unsatisfactory. As a consequence, dynamic structural analyses with both horizontal ground-motion components become more common, both in research as well as in practice. A review of code provisions regarding selection and scaling of ground motions for bi-directional analysis has, however, revealed that the guidelines provided are frequently inconsistent or are lacking transparency regarding the underlying assumptions. The aim of this study is to shed some light on a number of aspects involved when selecting and scaling records for bi-directional analysis and post-processing results of such analyses.